Postal

Postal is a self-hosted mail server designed as an open-source alternative to SendGrid or Mailgun. Handles outbound and inbound, RESTful API, multi-domain. Operationally heavier than just running Postfix.

Judged purely as an API. What the request contract guarantees on retry, how complete the webhook event coverage is, whether suppressions are readable and writable programmatically, and how much the message log retains when something needs debugging in production.

Against high-frequency programmatic sends where a missed delivery is a product failure, Postal covers webhook coverage, event stream, the suppressions API, batch sending, and SDK breadth, and does not cover idempotency keys. Whether that gap matters depends on how central those are to the build.

• Idempotency keys: No
• Webhooks: Yes
• Event stream: Yes
• Operating since: Not published
• Suppressions API: Yes
• Best published rate per 1,000: Tiers not published in comparable form
• Batch sending: Yes
• SDKs: node, ruby, php
• Deliverability: You own it. Reputation depends on your IP, warmup discipline, and authentication.

You own it. Reputation depends on your IP, warmup discipline, and authentication.

Teams with infra ops capacity that want full control of their mail delivery.